Consumable artillery components



June 28, 1966 s, AXELRQD ET AL 3,257,948

CONSUMABLE ARTILLERY COMPONENTS Filed Aug. 25, 1965 wank/v6 INVENTORS SYDNEY AXELROD VLADIMIR MIRKO BY W. W a 7 I W ATTORNEYS 3,257,948 Patented June 28, 1966 United States Patent Office 3,257,948 CONSUMABLE ARTILLERY COMPGNENTS Sydney Axelrod, New York, and Vladimir Mirko, Brooklyn, N.Y., assignors to the United States of America as represented by the Secretary of the Army Filed Aug. 23, 1963, Ser. No. 304,744 8 Claims. ((Il. 102-43) The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to us of any royalty thereon.

This invention relates to an improvement in the manufacture of consumable cartridge cases, flash tubes, primer bodies, and other artillery components. These novel components possess the necessary physical properties of strength, rigidity, toughness, and the like, and in addition, are completely burned and leave no residue upon firing.

The advantages of consumable cartridge cases and their manufacture from nitrocellulose compositions are well known in the art. However, the use of highly inflammable or explosive materials for shell cases introduces an additional hazardous element into the manufacture and handling of completed shells. Moreover, cellulose nitrate does not possess desirable mechanical characteristics for many purposes and is also susceptible to Water absorption without a protective coating.

It is therefore the object of this invention to provide consumable cartridge components having advantageous mechanical and physical characteristics. It is an additional objectof this invention to provide consumable cartridge cases which are not highly inflammable under ordinary conditions.

, The foregoing objects as well as others are achieved in accordance with this invention by the novel use of foamed thermosetting resins for the fabrication of consumable artillery components.

In the appended drawing is shown a longitudinal section with the ends broken away of a consumable shell casing of foam thermosetting resin having a cellular structure that is completely combustible leaving no ash or residue when the cartridge is fired. The casing is notonly combustible but also burns with the charge that may be within the casing and is completely consumed. The plasticity of the material readily permits the casing tobe molded to any desired shape.

, The utility of these thermosetting foams as consumable artillery items is due to the cellular structure of these compositons. Due to the rapidity of combustion of propellant compositons, inert components often do not have time to be completely burned and leave a residue which isundesirable and which may be detrimental to the satisfactory functioning of theitem. This incomplete burning is due to the lack of suflicient burning surface. However, the foam structure is readily consumed by the combustion because the cellular structure increases the total surface area and decreases the mass. This burning is characteristic of 'rigid foams but not of flexible or semiflexible foams which soften or melt and do not have the required burning characteristics. It has been found that the cellular structure of the foam is of considerably greater significance for complete combustion than the chemical composition.- In addition, the rigidity of the foam gives the items structural strength.

These rigid cellular structures are formed by mixing two or more ingredients resulting in a mass which is poured, injected or otherwise introduced into a mold cavity. The reaction between the ingredients in the mix is completed in the mold cavity and may require heating from an outside source in order to go to completion, dependingupon the specific resin system used. Since the foaming resins readily flow into and fill cavities, there is no limitation to the shapes obtainable except for the practical problem of mold assembly on disassembly. Items such as consumable cartridge cases, consumable flash tubes, and consumable primer bodies have been formed and tested and found to function satisfactorily. Such rigid foamed components leave no residue and are smokeless.

Resinous materials suitable for the construction of these components must be rigid as well as impact and tear resistant when cured. It is of importance that the porous structures consist of small, uniform, non-connected cells.

The thermosetting resins which can form satisfactory cellular masses include the polyurethane, epoxy, phenolic, and other resin types. The gas for foaming may be produced by the addition of blowing agents, that is, compounds which will form a gas at the temperature of the curing reaction either by, decomposition or by vaporization. In the case of polyurethanes and polyisocyanate modified resins, the gas for foaming may be produced by the addition of an excess of polyisocyanate and water. The reaction produces carbon dioxide as well as active hydrogen compounds which further react and cross-link with the resin ingredients to aid in its cure.

In order to produce foamed resins having small, nonconnected cells, it is necessary to trap the gas producing the foam at a great number of points. The use of viscous cyanate group terminated prepolymer.

reacting masses helps prevent the loss of coalescence of gas bubbles and with the additional use of foam stabilizers, a more precise control of cell size can be ob- X X I y- I 1 CH2 -CH2 in the following cases: (1) where X is -OH and Y is CH OH, i.e., the novolacs; (2) where X is i.e., the reaction product of the novolacs with epichlorohydrins; and (3) Where X is --NCO and Y is H, i.e., polymethylene polyphenyl isocyanates.

Polyurethane resin foams useful to this invention are produced by the reaction of polyesters or polyethers with a polyisocyanate and the further reaction with a curing agent containing a source of water and an amine type catalyst. The polyesters and polyethers used are of the type that terminate with hydroxyl groups. They react with an excess of the polyisocyanate to produce an iso- Further polymerization and cross-linking is effected with the aid of Water and the catalyst. The water reacts with the terminal -NCO groups to not only cross-link but also to produce carbon dioxide gas at a rate controlled by the catalyst. As the polymerization proceeds the viscosity increases and the resin expands due to the formation and entrapment of the carbon dioxide gas. The reaction is exothermic and the heat liberated aids in curing the foam.

The curing agent consists of a mixture of 40-60% of a salt containing chemically bound water, 20-30% of a tertiary amine, 10l5% of a surfactant and lO-15% of a silicone oil. The salt containing chemically bound water may be sodium acetate trihydrate, sodium dihydrogen orthophosphate monohydrate, cadmium acetate tri- Acid catalysts used for curing may be phenol sulfonic acid, benzene sulfonic acid or concentrated sulfuric acid. The fugacious material used as a blowing agent may be for example, diethyl ether, cyclohexane, and other hydrohydrate or other hydrate salt which Will decompose with- 5 carbons such as hexane, heptane, or octane. The aquein the temperature range used to cure the polyurethane ous reaction product of a phenol and an aldehyde is prefoam resin. Tertiary amines suitable for use include pared by reacting at least one mole of a phenolic compyridine, Z-dimethylaminoethanol, N-methylmorpholine, pound, such as phenol itself, cresol, xylenol, and resortriethylamine, and others. The surfactant used may be cinol with an excess of aqueous aldehyde such as formalan ethylene oxide condensate with fatty acids, such as dcl1yde,acetaldehycle, and furfuraldehyde, in the presence oleic and stearic, or with the amides of such acids. The of an alkaline catalyst, such as sodium or potassium hypolyoxyethylene sorbintan esters, e.g., polyoxyethylene droxide, sodium bicarbonate, and other basic materials, sorbitan monopalmitate, polyoxyethylene sorbitan monoand finally removing most of the excess water under oleate, are also useful surfactants. The silicone oil is vacuum. preferablya dimethyl siloxane polymer. In the preparation of the foamed resins used in this The polyethers and polyesters useful in producing polyinvention, the ingredients may be mixed simply by poururethane foams are viscous liquids. Suitable polyethers ing one into the other and stirring thoroughly either by include polyoxyalkylene glycols such as polyethylene hand or mechanically. There is no preferred rate of glycol, polypropylene glycol, and others. Suitable polyaddition. The mixtures of resin and other ingredients esters can be prepared by reacting dicarboxylic acids such (e, blowing a nt, hardeners) must b oured into the as adipic, sebacic, succinic, and phthalic acid with an exmold immediately, Control of the foaming and the cess of a glycol selected from the l W r m s f th size of the voids in the product is predetermined by conhomolosous series, for example ethylene glycol, p py trolling the starting materials used and the curing and y and hutylene g y lseful polyisocyanates infoaming conditions which are known to those skilled in clude, among others, the fQllOWiHgI P y the art. Many of the resins may be prepared by mixing diisocyanate, P Y y P y components commercially available in unit packages. methoxy-4,4-d'iisocyanate, naphthalene-1,5-diisocyatnat Otherwise the curing or hardening optimum foaming conhaphthaleherl,s-diisocyanate, naphthalene-2,7 dil'socyaditions must be determined for each composition. hate, as Well as a polymethyle116 P yp ivSOcyanate In all cases, the molds must be coated with a mold recording to the Previously given generahled Structural lease agent. A variety of release agents may be used, formula in Which Flhe Value is pffildominantly including Teflon spray, polyvinyl alcohol spray, silicone P Y foamed resins y be Produced y miXhlg P oil spray, silicone grease, and others. glycidyl ethers With a hardener and a blowing agent Below are given several illustrative examples showing The harden acts to cross-link the y y Chains and typical methods of carrying the present invention into to produce a three dimensional resin. The blowing agent practice decomposes upon heating to release an inert gas, e.g., E l 1 nitrogen or carbon dioxide. The cross-linking is exothermic and the heat liberated aids in further curing the of pourable polyefthylene glycohaqlpate i resin as well as in decomposing the blowing agent to mlxeid h 18 grams of Curing agent consisting of release the gas which causes the resin hardener mixture 40 gredlems m parts by Welght as follows: 10% dlmethyl to foam as the ingredients react. additional heating.

The hardeners or cross-linking agents for the epoxy resins include dibasic acids and their anhydrides, for example succinic and phthalic acids and theiranhydrides, and diamines, for example, ethylenediamine, diethylenetriamine, triethylenetetramine, meta-phenylenediamine, diaminophenylsulfone, and others. The hardeners may contain, in addition, a tertiary amine such as triethylamine Post curing requires siloxane having a viscosity of 100 centistokes at 100 F., 25% triethylamine, 55% sodium acetate trihydrate, and 10% polyethylene sorbitan palmitate. This mixture is poured with stirring into 400 grams of polymethylene 0 polyphenyl isocyanate having a molecular Weight not in excess of 400 and corresponding to the previously given structural formula wherein the n value is predominantly 1. The resulting mixture is poured immediately into a mold previously treated with silicone grease and preheated to about 125 F. It is simultaneously foamed or Z-dimethylaminoethanol, to act as a catalyst for the v o cross-linking reaction. Suitable blowing agents for epoxy and cured fleatmg In the mold at about for foamed resin include sodium bicarbonate, ammonium one hoour then H cured for an addltlonal hour carbonate, dinitrosopentamethylenetetramine, and N,N'- at 400 Tne l 13 then cooled to room temperadimethyl N,N'-dinitrosoterephthalamide. Suitable glycand the Cured m e idyl ethers can be prepared by the action of epichloro- The above.amounts of .mgledlents. e sumclelllt f a hydrin on polyhydric phenols such as resorcinol, novolac 90 cartridge .6356 having a f thlckness A Inch resins, bis(p hydroxyphenyl) methane 2,2 bis(p hydmXy a length of 20.5 1nches and a diameter of 4.5 inches at phenyl) propane and other bisphenols. the base and 3.5 inches at the mouth.

Phenolic foamed resins are produced by curing a par- E l 11 tially reacted aqueous reaction product of a phenol and an aldehyde in the presence of a readily volatile substance which evaporates at the curing temperature of the phenolic 100 grams of a diglycidyl ether corresponding to the formula OH; OH I C II; C H;

wherein n is zero in the case of at least of the molecules and one for the remainder, are mixed with 12 grams of diethylenetriamine and 10 grams of N,N'-

resin. The curing reaction is exothermic and the heat thus liberated aids in the further curing of the foam and also the production of gas, through volitalization, causing the curing resin to foam.

dimethyl-N,N'-dinitrosoterephthalamide. The mixture is introduced into a flash tube mold, previously coated with silicone grease, having dimensions as follows: length, 17 inches; inside diameter, 1.1 inches, and outside diameter, 1.58 inches. The resin is cured in the mold at a temperature of 350 F. for one half hour, at the end of which time the mold is cooled to room temperature and the resin removed.

The epoxy resin is a hard, rigid structure which completely fills the mold.

Example 111 A liquid resinous reaction product of phenol and formaldehyde is prepared by mixing ingredients in the ratio of 94 grams phenol, 75 grams of 40% aqueous formaldehyde, and 1 /2 grams sodium hydroxide for 3 hours and heating for 3 hours at a temperature of 175 F., cooling and acidifying to a pH of 6 with sulfuric acid and partially dehydrating the product to a water content of approximately 15% by continued heating at 175 F. under a pressure of 35 cm. Hg for a period of one half hour, and finally cooling to room temperature. 70 grams of this resinous product is mixed with 22 grams of ethyl ether and then 8 grams of concentrated sulfuric acid. The mixture is stirred and quickly poured into a flash tube mold, previously coated with silicone grease and having dimensions as follows: length, 17 inches; inside diameter, 1.1 inches, and outside diameter, 1.58 inches. The heat generated is suflicient to simultaneously foam and cure the phenolic resin. The mold is allowed to remain at room temperature for an additional hour after cooling to ambient temperature and then the molded resin removed.

As in the case of the other resinous materials, the foam completely fills the mold and sets to a hard, rigid material.

The plastic structures found most desirable and obtained by the ingredients and foaming conditions delineated in the examples above are porous and consist largely, that is to the extent of at least 75%, of closed non-connected cells. The largest cells are 0.03 inch in diameter and approximately 85-95 of the cells are 0.003 inch in diameter or smaller.

Firing tests of the 175 mm. Gun M113, using a rigid polyurethane flash tube and the M6 Propellant Charge (composition: nitrocellulose (containing 13.15 percent N)--86.1%, dinitrotoluene9.9%, dibutylphthalate 3.0%, and diphenylamine1.0%) gave satisfactory ballistic results without any residue remaining from the polyurethane tube. Previously, paper tubes had been used and had left residue in the gun. Firing tests with the 90 mm. Gun M41 using a rigid polyurethane cartridge case to replace the T24B1 cartridge case gave the following comparative results using the same propellant charge for each cartridge case:

I Table I BALLISTIC EFFECT OF FOAMED POLYURETHANE CAR- TRIDGE CASE The consumable foamed plastic cartridge cases of this invention are all highly cross-linked materials not significantly affected by temperature extremes and should function satisfactorily under both tropical and arctic conditions. The dimensional changes with absorption of water vapor from the atmosphere is not such as to affect the chambering of cartridge cases in a gun. The plastics are all compatible with and not noticeably affected by nitroglycerine and other propellant components.

Having described the invention what is claimed and desired to be secured by Letters Patent is:

1. A consumable shell casing for artillery ammunitio in which the consumable shell casing comprises a rigid, cross-linked, thermosetting resin having a cellular structure.

2. A consumable shell casing according to claim 1 wherein the said casing is a cartridge case.

3. A consumable shell casing according to claim 1 wherein the said casing is a flash tube.

4. A consumable shell casing according to claim 1 wherein the thermosetting resin is a polyurethane plastic.

5. A consumable shell casing according to claim 1 wherein the thermosetting resin is an epoxy plastic.

6. A consumable shell casing according to claim 1 wherein the thermosetting resin is a phenol-formaldehyde plastic.

7. A consumable shell casing for artillery ammunition in which the consumable shell casing comprises a rigid, cross-linked, thermosetting resin having a cellular structure and consisting predominantly of closed nonconnected cells, the said cells having a maximum size of 0.03

inch in diameter and at least of the said cells having a maximum diameter of 0.003 inch.

8. A consumable shell casing for artillery ammunition in which the casing comprises a molded shell consisting of a rigid, cross-linked thermosetting resin having a cellular structure with unconnected cells.

References Cited by the Examiner UNITED STATES PATENTS 664,116 12/ 1900 Barrallon 10240 2,632,391 3/1953 Kintzinger 10243 2,831,820 4/1958 Aase et al. 2602.5 2,979,469 4/1961 Shannon et a1 260-25 3,027,286 3/1962 Kurhan 20646 3,051,665 8/1962 Wismer et al 2602.5 3,075,926 1/ 1963 Stewart et al 20646 3,084,824 4/1963 Kuzma et al 20646 3,085,896 4/1963 Britt et al 260--2.5 3,093,600 6/1963 Spencer et al 2602.5 3,095,813 7/1963 Lipinski 10243 3,098,444 7/ 1963 Wal-key et a1 102-43 OTHER REFERENCES Scientific American, September 1947, pp. 119-121, Expanding Fields for Expanded Plastics, by Charles A. Breskin.

BENJAMIN A. BORCHELT, Primary Examiner.

SAMUEL FEINBERG, Examiner.

R. F. STAHL, Assistant Examiner. 

1. A CONSUMABLE SHELL CASING FOR ARTILLERY AMMUNITION IN WHICH THE CONSUMABLE SHELL CASING COMPRISES A RIGID, CROSS-LINKED, THERMOSETTING RESIN HAVING A CELLULAR STRUCTURE. 